It is from an old phone. Will it delete data on my phone? Will that amount of space now be available on iCloud?
So if I back up my phone today, the old back-ups don't matter any more? Will the data that was backed up be deleted? Like all the photos, etc?
Yes, if you already have all the data (photos, etc.) you need from the old backups on your phone. If the data is on your phone now, it will be included in your new backup. Then you won't need the old backups anymore. You might want to back it up to your computer using iTunes before deleting the old backups. To do this, connect your phone to your computer, open iTunes, click on the name of your phone in iTunes, go to the Summary tab and click Back Up Now. After backing it up successfully, you can delete your old backups from your account, freeing up space to back up to iCloud again.
The only reason you would want to keep old backups is if you still needed to restore some of the data from them to your device.
It will only delete it from iCloud, freeing up space in your account. It won't do anything to the data on the data on your phone.
What happens if I delete an old backup in iCloud?
